利用阶段pH控制提高灵芝深层发酵合成三萜能力的研究

Enhanced Triterpene Biosynthesis in Ganoderma lucidum by Staged pH Control during Submerged Fermentation

采用3 L发酵罐考察不同pH发酵条件对灵芝(Ganoderma lucidum)菌丝体生长和灵芝胞内三萜合成的影响。结果表明,在pH4.5条件下,菌丝体干重和胞内三萜含量均最高,分别为12.31 g·L^-1和237.91 mg·L^-1。根据不同pH条件下,灵芝发酵过程中菌丝体的比生长速率、三萜比合成速率的变化,提出四阶段pH控制策略:0~26 h pH自然,26~36 h pH4.0,36~81 h pH4.5,81~168 h pH5.0,在此条件下,在3 L发酵罐中发酵,灵芝的菌丝体干重为14.18 g·L^-1,比对照(pH自然)和pH4.5时分别提高59.15%和15.19%,灵芝胞内三萜含量279.59 mg·L^-1,比对照和pH4.5时分别提高47.72%和17.52%;在50 L发酵罐中进行发酵验证,菌丝体干重和灵芝胞内三萜含量分别为13.54 g·L^-1和256.97 mg·L^-1。本研究的四阶段pH控制策略可较大幅度提高灵芝胞内三萜产量,且该发酵工艺操作简单易行,可为利用规模化深层发酵技术生产灵芝胞内三萜提供有益的参考。

Using a 3 L bioreactor, effect of pH on mycelial growth and triterpene production of Ganoderma lucidum were investigated. The results showed that dry mycelial weight and triterpene concentration were greater at pH4.5 than other consistent pH conditions, reaching 12.31 g· L^-1 and 237.91 mg· L^-1, respectively. Based on mycelial specific growth rate and specific synthesis rate of triterpenes during fermentation of G. lucidum under different pH conditions, a four-stage pH control strategy was proposed: 0-26 h, natural pH;26-36 h, pH4.0;36-81 h pH4.5;81-168 h, pH5.0. Using this pH control strategy at 3-L scale, the dry mycelial weight was 14.18 g· L^-1, which was increased by 59.15% and 15.19% compared with the control group(natural pH) and pH4.5, respectively;and the concentration of intracellular triterpenes was 279.59 mg·L^-1, which was increased by 47.72% and 17.52% compared with the control group(natural pH) and pH4.5, respectively. When cultured in a 50 L bioreactor with the four-stage pH control strategy, G. lucidum yielded 13.54 g·L^-1 dry mycelial weight and 256.97 mg·L^-1 intracellular triterpenes. The simple and easy-to-conduct staged pH control strategy improved triterpene biosynthesis effectively and provides a reference for scaled production of G. lucidum triterpenes.